I. Field of the Invention
The present invention relates generally to colorized durable, highly retroreflective materials, particularly colorized retroreflective materials for application to garments which retain both color and high retroreflectivity through many laundering cycles.
II. Related Art
Retroreflective materials of various kinds have been in use for many years. Applications have included road paints, road signs and various kinds of personal protective equipment including wearing apparel. In order to improve nighttime visibility and safety of pedestrians, cyclists, roadway workers, joggers and others who might otherwise be difficult to identify, they have been provided with clothing having retroreflective materials attached which are designed to reflect light back in the direction of incidence. In this manner, incident light such as that of automobile headlights is reflected back to the automobile, making the presence of the wearer clearly visible to the driver of the vehicle. The same easy visualization can be obtained using spotlights, searchlights and even flashlights.
Prior retroreflective technology for textiles and garments includes an array of transparent retroreflective elements partially embedded with a reflective undercoating in a binder layer which, in turn, binds the embedded beads to a layer of material which can be fixed to an article of clothing. The retroreflective elements are generally spherical glass microbeads. The technology has been generally based on one of several techniques.
One technique involves heat transfer films in which glass beads are hemispherically vapor-coated with a reflective material (silver, aluminum or a clear mirror coat used on white/clear reflective films). These beads are then deposited on a bead-bonding adhesive such that the reflective-coated side is in contact with the bead-bonding adhesive and the non-coated side is exposed. The bead bond adhesive is then coated with a second adhesive which provides adhesion to a garment. This adhesive is generally a hot-melt adhesive designed for heat lamination to a fabric. Alternatively, the second adhesive may be a pressure-sensitive adhesive. However, pressure-sensitive adhesives generally are not satisfactory for use on fabrics exposed to multiple laundering cycles.
Another approach involves retroreflective fabrics. These fabrics are quite similar in construction to heat transfer films, however, in this case a fabric layer is applied and bonded to the second adhesive directly after coating and before application to a garment. This produces a reflective fabric construction that can be stored and later sewn onto garments.
A third approach is found in reflective transfer paper. In this approach, glass beads are bonded to a transfer paper using a thin coating of polyethylene. A vapor coat of reflective material is then applied to the top of the glass beads. Garment and bead-bonding adhesives (generally heat-transfer adhesives) are then printed over the coated side of the glass beads. This can be done using a screen-printing process, in which a prescribed design is printed in adhesive on the transfer paper. This transfer is then applied to a garment by heat lamination. The polyethylene liner only releases beads that are held by the printed heat transfer adhesives. The transfer paper is then removed leaving reflective glass beads according to the pattern of the printed adhesives.
It is also known to provide retroreflective articles having launderably durable bonded retroreflective elements. Such a material is illustrated and described, for example, in U.S. Pat. No. 5,976,669 in which an array of retroreflective elements are arranged and partially embedded in a binder layer that contains a solid polyurethane blend.
It is also known to provide colorized retroreflective materials by providing a colorized layer on the underside of partially embedded retro reflective elements overlaid by a reflective layer. Examples of this type are found in U.S. Pat. Nos. 5,344,705; 5,503,906 and 5,620,613. The vast majority of reflective material incorporated into personal protective equipment is and has been silver in color, however.
Vinyl-based materials that are not made with glass-bead retroreflective technology have also been used. Materials of this type that are currently being used have generally been found to be somewhat uncomfortable for the wearer and are, accordingly, less desirable for use on clothing.
While progress has been made, demand is increasing for retroreflective garments that not only provide a high level of reflectivity but also which are comfortable for the wearer and aesthetically pleasing. This includes a large demand for reflective material that matches the colors of uniforms, for example. Many companies also have large numbers of employees that work in or near traffic who need retroreflective garments but which would preferably reflect other colors than silver which might clash with corporate logo images or the overall appearance of the uniform.
Present, commercially available colorized retroreflective materials have been found lacking. They do not provide either the level of reflectivity or durability that is necessary for use in uniforms or other garments worn on a daily basis. Such garments are generally subjected to hard use and are laundered a total of 50 or more times before being removed from service. Therefore, there is a need for retroreflective materials incorporated in such garments which enable the items to maintain a high level of reflectivity and appearance throughout the useful life of the garment, which would encompass numerous laundering cycles.
The preferred standard for the level of reflectivity that the reflective material should initially have is a reflectivity of 330 cd/lux/m2. The standard also requires the material to maintain a reflectivity of more than 100 cd/lux/m2 throughout the life of the garment (ANSI/ISEA 107-2004, level 2, reflectivity measured at an observation angle of 12′, and an entrance angle of 5°).